The project objectives are: 1) to develop quantitative measures of phonation in normalcy and patients with laryngeal pathology: 2) to determine which measures of phonation are sensitive to laryngeal pathologies; and 3) to determine the patterns of vocal fold movement associated with particular acoustic attributes of phonation. A study was completed assessing the validity of using an acoustic measure of frequency perturbation (random variation in cycle length) for the non-invasive detection of laryngeal pathology. Ninety-five normal subjects were tested to determine the relationship of age, sex, phonatory intensity, fundamental frequency, maximum phonation length and drinking and smoking histories with frequency perturbation. A multiple regression model employing 4 factors was able to predict frequency perturbation in the normal population with 70% accuracy. This model was used to predict the 90% normal confidence interval for normal expected of frequency perturbation for 31 patients with laryngeal carcinoma, nodules, polyps, unilateral paralysis and edema. The measured frequency perturbation exceeded the normal expected level in only 35% of patients and was accurate only for the detection of carcinoma. Thus, frequency perturbation was not a good measure of phonatory abnormalities due to laryngeal pathology. These results suggest that random variations in frequency do not result from morphological changes in the vocal folds in the majority of cases. Other acoustic measures are now being examined for their sensitivity to laryngeal pathology. Investigations will be initiated to determine the relationship between patterns of vocal fold vibration and acoustic attributes of phonation in normalcy and laryngeal pathology.